srecord MatchJob(L<S> input, L<S> struct) {
  new SS vars;
  
  void clear { input = new L; struct = new L; }
}

static MatchJob matchJob_solved() { ret MatchJob(new L, new L); }
sbool matchJob_isSolved(MatchJob mj) { ret mj != null && empty(mj.input) && empty(mj.struct); }

static MatchJob matchJob_map(O f, MatchJob mj) {
  ret MatchJob((L<S>) callF(f, mj.input), (L<S>) callF(f, mj.struct));
}

static void matchJob_apply(O f, MatchJob mj) {
  mj.input = (L<S>) callF(f, mj.input);
  mj.struct = (L<S>) callF(f, mj.struct);
}